Heat insulation



Patented Oct. 25, 193s a I Z,l34,340

UNITED STATES PATENT OFFICE HEAT INSULATION Jesse Hopkins Plummer, Newark, Ohio, assignor to Owens-Illinois Glass Company, a corporation of Ohio No Drawing; Application October 3, 1935, Serial No. 43,389. Renewed April 1, 1938 11 Claims. (Cl..154-44) My invention relates to heat insulating mate- I have demonstrated by tests that powdered rials and, more particularly, to insulation for use calcium fluoride when added as a loading matewith moderately high temperatures, as, for exrial to glass wool, materially increases its insuample, stove insulation, to be used at temperalating properties. For example, I have loaded tures of l000 F. or lower. The invention in its glass wool having a density of three pounds per 5 preferred form. involves the use of low density cubic foot with one-third its weight of powdered: inorganic insulating material such as glass wool calcium fluoride. Tests of this material with a or other inorganic fibrous materials in bulk, in hot surface temperature of 600 F. and a cold matted, or in felted form. surface temp r tu e of 65 F., show that the An object of the invention is to improve the amount of heat transmitted'is much less than 1 insulating qualities of such materials by the comwhen the said loading material .is omitted and bination therewith of a loading material of a also much less than if the same glass wool is character to greatly reduce the heat radiation. packed at a density of four pounds per cubic foot,

For the purpose of describing the theory inor, in other words, having the same density as volved in the present invention, I refer to glass the combined glass wool and packing of calcium 1 wool in matted or felted form as an example of fluoride. Tests of the character indicated have a base which I have employed withgood results demonstrated that the calcium flouride exerts in practicing the invention. This base may cona much greater influence upon the insulating 00- sist of fine glass fibers in bulk and having a low eflicient than the same quantity of glass wool.

density, as, for example, three pounds per cubic As a further example of comminuted material 20 foot. When such an insulating base has added which is transparent .to the shorter infra-red thereto a loading material which is transparent heat rays, silica in powdered form may be noted to that portion of the infra-red heat rays where as one of the materials which I have found to the energy is greatest, the insulating properties be suitable for the purposes of the present invenof the material are greatly improved. tion. The alkali halides may also be noted. 25

The theory behind the use of such a loading These included the salts consisting of sodium, material may be described as follows: A large part potassium or calcium combined with elements of of the heat energy which escapes through any the halogen group (comprising chlorine, fluorine, insulation of the character indicated, is transbromine and iodine) mitted by radiation. This energy does not neces- It may be noted that with the insulating ma- 30 Sa ly v to P through the material in the terials of the general character herein referred form of unbroken r y but may he eheelbed and to, there is very little heat transmitted by con- Ie-Ie-diated repeatedly the fibers or the like duction and convection. Accordingly, any means eempflsihg the insumtmn' 4 materials which for reducing the amount of radiation in the mang f 2 12; zi g g gfgigg g' gg 31 ner above described will correspondingly increase then, the heat radiation can be blocked by ilzzitemefiectiveness of the material as a heat insu some material which has a very low emissive power, the insulating efliciency of a low density Mwlfications may be resorted to within the 40 material may be greatly increased. spirit 3 Scope of my invention- 40 According to my invention, this is done by em- I elalmploying a substance which is transparent to the An insulating matenel eempflsmg base short wave-length infra-red heat rays, and loadof inorganic Solid material open formation ing it into the insulation base as a finely divided Presentmg a large surfaee area dispersed powder. Radiation from a hot surface covered throughout the p of e meteneland e 4 by such insulation, is so weakened by multiple omminuted loading material forming a coating reflections from the enormous surface area of for Salli surfeee, Said loading materlel being 2 these powder particles, that virtually none of it substahee whleh is transparent tF0 the Portion penetrates any substantial distance into the body of the mire-red rays Withm the Zone of test of insulation, and there is practically no reheat e 5o radiation since such a substance does not radiate An msulatmg matenel eompllsmg s of Strongly when heated. c m fluoride is an, inorganic solid material in open formation preexample of a substance known to be transparent sentine a large surface ea di p ed u ut to that portion of the infra-red where the enthe body of said material, and a comminuted ergy is greatest. loading material forming a coating for said sur- Ii face, said coating material consisting of calcium fluoride.

3. A high temperature heat insulating material comprising a low density base of inorganic fibrous material, and a coating for said base of powdered material which is substantialiyi transparent to high temperature infra-red 4. A high temperature heat insulating material comprising a low density base of inorganic fibrous material, and a powdered coating material for said base presenting a large surface area for radiation and consisting of a material which is transparent to that portion of the infra-red where the energy is greatest. v

5. A high temperature insulation comprising a low density base consisting of glass fibers in matted or felted form, and a loading material transparent to that portion of the infra-red heat rays where the energy is greatest.

6. A low .density insulating material comprising a base of inorganic fibrous material in matted or in felted form, and a loading material forming a coating for said base and greatly increasing the radiating surface area 'of the insulation, said loading material being transparent to that portion of the infra-red heat rays where the heat energy is greatest.

'1. A low density insulating material comprising a base of inorganic fibrous material in matted or in felted form. and a loading material forming a coating for said base and greatly increasing the radiating surface area of the insulation, said loading material consisting ofcalcium fluoride.

8. A high temperature insulation comprising a low density base consisting of glass fibers in matted or felted form, and a loading material.

forming a coating .10! said fibers. said loading material consisting of calcium fiuoride.

9. An insulating material comprising a base of inorganic solid material inopen formation presenting-a large surface area dispersed throughout the body of said material, and a comminuted loading material forming a coating for said surface, said loading material consisting of silica in comminuted form.

10. A high temperature heat insulating material comprising a low density base of inorganic material in open formation presenting a large surface area dispersed throughout the body of said material, and an alkali halide in powdered form and substantially transparent to high temperature infra-red rays.

11. A low density insulating material comprising a base of inorganic fibrous material in matted or felted form, and a loading material in com minuted form forming a coating for said base and greatly increasing the radiating surface area of the insulation. said loading material consisting of an alkali halide whichis substantially transparent to that portion of the infra-red heat rays where the heat energy is greatest.

' JESSE HOPKINS PLUMMER. 

